. Smithsonian miscellaneous collections. fter + i + .2 +.3+.2 — .2 -3-•3 +2 +.5+.3 .o+.3 .o+ .4 Year. + .3 ~-3 +. This table shows not only that there is a decreased pressure nearsunspot maximum throughout the year in the Tropics, but showsalso that the decrease is greatest near the equinoxes. 24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 104 It is universally accepted by meteorologists that the lower atmos-pheric pressure found in the Tropics is due to the greater heating ofthe atmosphere near the Equator by If one knew how muchthis observed pressure differed from the n
. Smithsonian miscellaneous collections. fter + i + .2 +.3+.2 — .2 -3-•3 +2 +.5+.3 .o+.3 .o+ .4 Year. + .3 ~-3 +. This table shows not only that there is a decreased pressure nearsunspot maximum throughout the year in the Tropics, but showsalso that the decrease is greatest near the equinoxes. 24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 104 It is universally accepted by meteorologists that the lower atmos-pheric pressure found in the Tropics is due to the greater heating ofthe atmosphere near the Equator by If one knew how muchthis observed pressure differed from the normal pressure at theEquator of a rotating earth at uniform temperature, it would be pos-sible to compute the relative amount of decrease in pressure betweensunspot minimum and sunspot maximum. With proper assumptions this normal could be calculated, but forthe present, at least, I have determined it graphically in figure 19,where the average observed pressure is plotted and a mean curvedrawn through it, as shown by the dotted Fig. 19.—A, normal mean pressure at each io° latitude of earth; B, estimatednormal pressure on earth of uniform temperature. The average observed pressure is taken from World Weather,p. 29, as follows: Table 7.—Average observed pressure in millibars Equator Pole Latitude o 10 20 30 40 50 60 70 80 90 Mean pressure north ion ion 1013 1016 1017 1014 1012 1013 1014 1015 Mean pressure south ion 1012 1015 1018 1014 1003 992 990 991 From figure 19 the estimated pressure at the Equator on a rotatingearth of uniform temperature is estimated at mb., while thenormal pressure at the Equator is mb. The difference betweenthe observed and estimated pressure is mb. Near sunspotmaximum the pressure at the equinoxes averages mb. lower at sun-spot maximum than at sunspot minimum, which, divided by mb.,gives a percentage increase of 18 percent. NO. 19 SUNSPOT CHANGES AND WEATHER CHANGES—CLAYTON 25 Another method of approach was the
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